rockchip: rk3399: add target type for evb based board

There are many boards share the board file and device header file with
rk3399 evb, add target type MACRO so that it is fixed instead of default
to the first target in "RK3399 board select".

Signed-off-by: Kever Yang <kever.yang@rock-chips.com>
diff --git a/configs/khadas-edge-rk3399_defconfig b/configs/khadas-edge-rk3399_defconfig
index e5a6523..ed4429d 100644
--- a/configs/khadas-edge-rk3399_defconfig
+++ b/configs/khadas-edge-rk3399_defconfig
@@ -3,6 +3,7 @@
 CONFIG_SYS_TEXT_BASE=0x00200000
 CONFIG_ENV_OFFSET=0x3F8000
 CONFIG_ROCKCHIP_RK3399=y
+CONFIG_TARGET_EVB_RK3399=y
 CONFIG_NR_DRAM_BANKS=1
 CONFIG_DEBUG_UART_BASE=0xFF1A0000
 CONFIG_DEBUG_UART_CLOCK=24000000